thankfully not yet. But I do know someone that went diving with a friend and wasn't able to stay put for their safety stop and ended up drifting to the top without realizing it and they did get some decompression sickness and had to go to a chamber. I wasn't there so I don't know the details, just heard the story. Must have sucked. Don't know why they couldn't stay down at the safety stop, might have been the one holding the surface marker and maybe that pulled him up, or he still had some air in his BC that he couldn't dump or thought he dumped... not sure.